000
AXPZ20 KNHC 170407
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE MAR 17 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...

THE ITCZ AXIS LIES ALONG A LINE FROM 06N76W TO 06N85W TO 03N106W 
TO 07N135W TO 06N140W. THERE IS NO SIGNIFICANT CONVECTION ALONG 
ITCZ.

...DISCUSSION...

THE DEEP LAYER LOW N OF HAWAII WILL WEAKEN AND MOVE NORTHEAST 
OVER THE NEXT DAY OR TWO...TEMPORARILY SHIFTING THE SUBTROPICAL 
RIDGE OVER N CENTRAL WATERS FARTHER NORTHWARD.  MUCH OF THE 
SHORTWAVE ENERGY ASSOCIATED WITH THIS CUT OFF LOW IS EXPECTED TO 
PHASE WITH THE NORTHERN STREAM AND MOVE EASTWARD THROUGH THE N 
WATERS.  MEANWHILE...THE TROUGHING ASSOCIATED WITH THIS LOW WILL 
BE RELOADED WITH ENERGY CURRENTLY SW OF THE LOW.  THIS PATTERN 
WILL MAINTAIN THE MEAN TROUGHING OVER NW WATERS TUE THROUGH THU. 
FARTHER N...A STRONG MID LATITUDE SYSTEM WILL BEGIN TO BRING NW 
SWELL TO N WATERS OVERNIGHT TONIGHT.

THE DEEP LAYER TROUGH CURRENTLY DRAGGING ACROSS THE NW GULF OF 
MEXICO WILL PULL SLOWLY EASTWARD OVER THE NEXT DAY OR 
TWO...CARRYING THE ASSOCIATED SURFACE COLD FRONT EAST THROUGH 
THE SOUTHWESTERN GULF OF MEXICO...AND SLACKEN THE PRESSURE 
GRADIENT OFF THE W CENTRAL COAST OF BAJA CALIFORNIA BETWEEN THIS 
TROUGH AND THE SUBTROPICAL PACIFIC HIGH. WINDS OFF OF THE BAJA 
HAVE BEEN BLOWING AS HIGH AS 25 KT. AT THE SAME TIME...STRONG 
NORTHERLY FLOW IS BEGINNING TO BLEED THROUGH THE ISTHMUS OF 
TEHUANTEPEC AS THE COLD FRONT IS FORCED EASTWARD THROUGH THE BAY 
OF CAMPECHE. A MORNING QUIKSCAT PASS REVEALED WINDS TO 20 KT IN 
THE FAR NORTHERN GULF OF TEHAUNTEPEC WHILE THE LATER ASCAT PASS 
AT 1540 UTC SHOWED WINDS HAD INCREASED TO 20 TO 25 KT. A MINIMAL 
GALE WIND EVENT IS EXPECTED IN THE GULF OF TEHUANTEPEC...
BEGINNING WITHIN THE NEXT 4-6 HOURS...AND LASTING THROUGH WED 
MORNING...WITH WINDS POSSIBLY DROPPING BELOW GALE FORCE DURING 
THE DAY TUE...BEFORE RETURNING TO GALE FORCE OVERNIGHT TUE NIGHT 
AND THEN DIMINISH FOR GOOD ON WED.

WINDS SHOULD CONTINUE TO BE ABOVE 20 KT THROUGH THE FORECAST 
PERIOD ACROSS AND DOWNWIND A SHORT DISTANCE OF THE GULF OF 
PAPAGAYO AS STRONG TRADE WINDS MOVE THROUGH CENTRAL AMERICA.  
THE HIGH PRESSURE RIDGE CURRENTLY OVER THE EASTERN GULF OF 
MEXICO IS BEGINNING TO SHIFT SOUTHWARD INTO THE NW CARIBBEAN AS 
THE COLD FRONT OVER THE WESTERN GULF EDGES EASTWARD...ALLOWING 
THE PRESSURE GRADIENT TO  BUILD BETWEEN THIS RIDGE AND THE 
CLIMATOLOGICAL LOW PRESSURE OVER NORTHERN COLOMBIA.  HIGH 
PRESSURE BEHIND THE WEAKENING COLD FRONT WILL MAINTAIN MODERATE 
TRADES IN THE CARIBBEAN THROUGH THE FORECAST PERIOD. A MORNING 
QUIKSCAT PASS ALSO SHOWED WINDS TO 20 KT DOWNWIND OF THE GULF OF 
PANAMA...WITH LITTLE CHANGE EXPECTED THERE OVER THE NEXT TWO 
DAYS.

THERE IS LITTLE CONVECTION OVER THE FORECAST AREA AT THIS TIME.  
WIDESPREAD SUBSIDENCE CAN BE FOUND OVER MUCH OF THE REGION SE OF 
A LINE FROM 18N102W TO 00N128W.  UPPER LEVEL CONFLUENCE ALONG 
100W IS INHIBITING CONVECTION IN THAT AREA WHILE 250 MB FLOW IN 
EXCESS OF 50 KT CAN BE FOUND BETWEEN 20N AND 25N...ALSO 
INHIBITING CONVECTION.  THE BEST CHANCE OF CONVECTION DEVELOPING 
THIS PERIOD WILL BE IN THE AREA S OF 20N AND W OF THE 
AFOREMENTIONED LINE WHERE PRECIPITABLE WATER VALUES ARE NEAR 2 
INCHES AND BROAD UPPER LEVEL DIFFLUENCE CAN BE FOUND ON THE 
LEADING EDGE OF THE TROUGH SUPPORTING TO LOW N OF HAWAII.  
CURRENTLY...SCATTERED MODEST CONVECTION LIES WITHIN 60 NM OF THE 
ITCZ BETWEEN 86W AND 99W...WHILE SCATTERED MORE SIGNIFICANT 
CONVECTION WAS OCCURRING FROM 08N TO 12N BETWEEN 120W AND 140W.

$$
SCHAUER CLARK/STRIPLING